Make the over-arching premise that the Joker has taken over in Arkham Asylum and unless Batman becomes committed as a resident in 24 hours, he will kill the staff. Because it takes place in Arkham Asylum Batman can face a different member of his rogues gallery every hour (every episode) while working his way through the Asylum searching for where Joker is hiding with the Administrators.

Yes, the idea is based on Arkham Asylum: A Serious House on Serious Earth (which informed the video game). I just think it would be an awesome TV series if done with a big budget.